WO2004049309A1 - Coding an audio signal - Google Patents

Coding an audio signal Download PDF

Info

Publication number
WO2004049309A1
WO2004049309A1 PCT/IB2003/004864 IB0304864W WO2004049309A1 WO 2004049309 A1 WO2004049309 A1 WO 2004049309A1 IB 0304864 W IB0304864 W IB 0304864W WO 2004049309 A1 WO2004049309 A1 WO 2004049309A1
Authority
WO
Grant status
Application
Patent type
Prior art keywords
parameters
audio signal
calculated
value
values
Prior art date
Application number
PCT/IB2003/004864
Other languages
French (fr)
Inventor
Erik G. P. Schuijers
Arnoldus W. J. Oomen
Matheus J. A. Mans
Original Assignee
Koninklijke Philips Electronics N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

Links

Classifications

    • GPHYSICS
    • G10MUSICAL INSTRUMENTS; ACOUSTICS
    • G10LSPEECH ANALYSIS OR SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/008Multichannel audio signal coding or decoding, i.e. using interchannel correlation to reduce redundancies, e.g. joint-stereo, intensity-coding, matrixing
    • GPHYSICS
    • G10MUSICAL INSTRUMENTS; ACOUSTICS
    • G10LSPEECH ANALYSIS OR SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/02Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis using spectral analysis, e.g. transform vocoders or subband vocoders
    • G10L19/032Quantisation or dequantisation of spectral components
    • G10L19/035Scalar quantisation

Abstract

In the method of coding the audio signal, the values of first parameters (P1,1), which represent aspects of the audio signal at a first instant (ti), are calcul ated to obtain first calculated values (Al,i). The values of second parameters P2,i), which represent the aspects of the audio signal at a second, later, instant (t2), are calculated to obtain the second calculated values (A2,i). The number of the first parameters (Pl,i) and the number of the second parameters (P2,i) differ. A subset (SUS2,i) of the second parameters (P2,i) is associated with a particular portion (SFRAi) of a frequency range (FR) of the audio signal This frequency range (FR) of the audio signal is preferably selected to cover all the f requencies present in the audio signal. The values (A2,i) of the subset (SUS2,i) of the second parameters (P2,i) are coded based on a difference of this subset (SUS2,i) and a subset (SUS1,i) of the first calculated value(s) (Al,i) associate d with substantially this same particular portion (SFRAi) of the frequency range (FR). Thus the differentially coded values (7) of the second parameters (P2,i) are obtained by coding the difference of the values of second parameters (P2,i and first parameters (P1,i) which are associated with substantially the same frequency subrange (SFRAi). This allows to differential code the parameters (Pl,I P2,i) even if the number of the parameters changes in time.

Description

Coding an audio signal

The invention relates to a method of coding an audio signal, an encoder for coding an audio signal, and an apparatus for supplying an audio signal.

Prior solutions in audio coders that have been suggested to reduce the bit rate of stereo program material include intensity stereo and M/S stereo.

In the intensity stereo algorithm, high frequencies (typically above 5 kHz) are represented by a single audio signal (i.e., mono) combined with time-varying and frequency- dependent scale factors or intensity factors which allow to recover a decoded audio signal which resembles the original stereo signal for these frequency regions.

In the M/S algorithm, the signal is decomposed into a sum (or mid, or common) signal and a difference (or side, or uncommon) signal. This decomposition is sometimes combined with principle component analysis or time- varying scale factors. These signals are then coded independently, either by a transform-coder or sub-band-coder (which are both waveform-coders). The amount of information reduction achieved by this algorithm strongly depends on the spatial properties of the source signal. For example, if the source signal is monaural, the difference signal is zero and can be discarded. However, if the correlation of the left and right audio signals is low (which is often the case for the higher frequency regions), this scheme offers only little bit rate reduction. For the lower frequency regions M/S coding generally provides significant merit.

Parametric descriptions of audio signals have gained interest during the last years, especially in the field of audio coding. It has been shown that transmitting (quantized) parameters that describe audio signals requires only little transmission capacity to re- synthesize a perceptually substantially equal signal at the receiving end. One type of parametric audio coders focuses on coding monaural signals, and stereo signals are processed as dual mono signals.

Another type of parametric audio coders is disclosed in EP-A-1107232. This parametric audio encoder uses a parametric coding scheme to generate a representation of a stereo audio signal which is composed of a left channel signal and a right channel signal. To efficiently utilize transmission bandwidth, such a representation contains information concerning only a monaural signal which is a combination of the left channel signal and the right channel signal, and parametric information. The stereo signal can be recovered based on the monaural signal together with the parametric information. The parametric information comprises localization cues of the stereo audio signal, including intensity and phase characteristics of the left and the right channel.

The parametric information is represented by parameters which characterize aspects of the audio signal in a frequency range of the audio signal for which the parameter is determined. The coded audio signal may comprise the coded monaural audio signal and a single global parameter (or a set of global parameters) which are determined for the complete bandwidth or frequency range of the audio signal to be coded, and/or one or more local parameters (or sets of local parameters) which are determined for corresponding sub-ranges of the frequency range of the audio signal (these sub-ranges of the frequency range are also referred to as bins). Many audio coding schemes employ parameters of which the amount varies over time, for example, in waveform-coders like MPEG-1 Layer-Ill (mp3), AAC (Advanced Audio Coding), the number of MDCT (modified discrete cosine transfer) coefficients can vary over time.

The not yet published European patent application no. 2002 02076588.9 (attorney's docket PHNL020356) discloses that the number of frequency sub-ranges (also referred to as bins) used for the parametric stereo representation can change from frame to frame.

The not yet published European patent application no. 2002 0277869.2 (attorney's docket PHNL020692) discloses that the corresponding parameters of successive frames can be encoded differentially over time. In this manner, the redundancy in the time direction can be removed. The number of parameters is identical in successive frames.

In E.G.P Schuijers, et.al, "Advances in Parametric coding for high-quality audio", presented at 1st IEEE Benelux Workshop on Model based Processing and Coding of Audio (MPCA 2002), Leuven Belgium, Nov.15, 2002, a parametric coding scheme is described that has been extended with a parametric stereo description. This description tries to model the binaural cues by means of three parameters: Inter-channel Intensity Differences (UD), Inter-channel Time Differences (ITD) and Inter-channel Cross Correlation (ICC). These parameters are estimated on a non-uniform frequency grid resembling the human auditory system. The number of frequency bins on this grid is typically 20. In the European patent application no. 2002 02077869.2 a scalable approach for the coding of these parameters has been proposed.

For this parametric coding scheme also the possibility exists to change the number of the LPC (Linear Predictive Coding) coefficients used to describe the spectral envelope from frame to frame.

A first aspect of the invention provides a method of coding an audio signal as claimed in claim 1. A second aspect of the invention provides an encoder for coding an audio signal as claimed in claim 10. A third aspect of the invention provides an apparatus for supplying an audio signal as claimed in claim 11. Advantageous embodiments are defined in the dependent claims.

In the method in accordance with the first aspect of the invention, differential coding is performed when the number of parameters is different in successive frames. This provides a more efficient coding of the parameters and thus less bandwidth will be required for the coded parameters. In the method of coding the audio signal, the values of the first parameters, which represent aspects of the audio signal at a first instant, are calculated to obtain the first calculated values. The values of second parameters, which represent the aspects of the audio signal at a second, later, instant, are calculated to obtain the second calculated values. The number of the first parameters and the number of the second parameters differ. A subset of the second parameters is associated with a particular portion of a frequency range of the audio signal. The values of the subset of the second parameters are coded based on a difference of this subset and a subset of the first calculated value(s) associated with substantially this same particular portion of the frequency range.

This allows to differential code the parameters even if the number of parameters changes over time.

In an embodiment as defined in claim 2, within a particular frequency subrange or bin, a single parameter has to be calculated for use in the first frame at the first instant. Within substantially this same frequency sub-range, several parameters have to be calculated for use in the second frame at the second instant. Each one of the several parameters for use in the second frame is differentially coded based on its difference with respect to the value of the single parameter.

If the frequency sub-ranges are not identical in that one of the several parameters is associated with a frequency sub-range which is not completely covered by the particular frequency sub-range, a correction may be applied in that this parameter is coded with respect to both the single parameter and a parameter associated with the frequency range not covered by the single parameter. hi an embodiment as defined in claim 3, within a particular frequency subrange or bin, several parameters have to be calculated for use in the first frame at the first instant. Within substantially this same frequency sub-range a single parameter has to be calculated for use in the second frame at the second instant. The value of the single parameter is differentially coded with respect to the mean value of the several parameters.

In an embodiment as defined in claim 4, the mean value is calculated as a weighted sum of the values of the several parameters. In an embodiment as defined in claim 5, all the weights are equal to one divided by the number of the several parameters of the first frame which correspond with the single parameter of the second frame.

In an embodiment as defined in claim 6, the weights are selected for each one of the several parameters to correspond to the size of the corresponding frequency sub-range. In an embodiment as defined in claim 7, the frequency sub-ranges are not identical in that the frequency sub-range of the single parameter only partly covers the frequency range of one of the several parameters, the contribution to the mean value of the value of this one parameter is less than the other ones of the several parameters. Preferably, its contribution depends on the percentage of the frequency range of the several parameters covered by the frequency sub-range of the single parameter only partly covering the frequency range of the several parameters.

In an embodiment as defined in claim 8, the audio signal is coded by different sets of parameters. Global parameters are calculated for the total frequency range of the audio signal. These global parameters allow decoding the audio signal with a basic (lower) quality. To allow an improved quality of the decoded audio signal, supplemental parameters may be coded. The number of these supplemental parameters may change over time. The number of the first parameters which are required during a first frame is smaller than the number of second parameters required during a successive second frame. Each one of the first parameters and the corresponding one of the second parameters cover substantially the same frequency sub-range. In frequency sub-ranges wherein a second parameter value has to be coded, this parameter value is differentially coded with respect to the value of the corresponding first parameter which is associated with substantially the same frequency subrange. In frequency ranges for which a second parameter has to be coded but no corresponding first parameter value is available, the value of the second parameter is coded differentially with respect to the global value(s).

In an embodiment as defined in claim 9, the audio signal is coded by different sets of parameters. Global parameters are calculated for the total frequency range of the audio signal. These global parameters allow decoding the audio signal with a basic (lower) quality. To allow an improved quality of the decoded audio signal, supplemental parameters maybe coded. The amount of these supplemental parameters may change over time. The number of the first parameters which is required during a first frame is larger than the number of second parameters required during a successive second frame. Each one of the first parameters and the corresponding one of the second parameters cover substantially the same frequency subrange. In frequency sub-ranges wherein a second parameter value has to be coded, this parameter value is differentially coded with respect to the value of the corresponding first parameter which is associated with substantially the same frequency sub-range. In frequency ranges for which a first parameter value is available but no corresponding second parameter has to be coded, nothing has to happen.

These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.

In the drawings:

Fig. 1 shows a block diagram of an encoder in accordance with an embodiment of the invention,

Fig. 2 shows a schematic representation of a situation wherein the number of parameters during a first frame is less than during a second frame, Fig. 3 shows another schematic representation of a situation wherein the number of parameters during a first frame is less than during a second frame,

Fig. 4 shows a schematic representation of a situation wherein the number of parameters during a first frame is higher than during a second frame,

Fig. 5 shows another schematic representation of a situation wherein the number of parameters during a first frame is higher than during a second frame,

Fig. 6 shows a schematic representation of a situation wherein the number of parameters during a first frame is less than during a second frame, and

Fig. 7 shows a schematic representation of a situation wherein the number of parameters during a first frame is higher than during a second frame. The same references in different Figs, refer to the same signals or to the same elements performing the same function.

Fig. 1 shows a block diagram of an encoder in accordance with an embodiment of the invention. An input IN receives an audio signal 1. The audio signal 1 has to be coded in such a way that a data-reduction is achieved. Data reduction is possible by representing certain aspects of the audio signal by parameters. These parameters define a certain aspect of the audio signal 1 within a particular frequency range of the audio signal 1. The particular frequency range of the audio signal 1 may cover all frequencies present in the audio signal 1, or may be a sub-range of the frequencies present in the audio signal 1. The parameters have to be determined regularly in time to be able to represent the changing audio signal 1. Usually, the parameters are determined and coded at regular time intervals called frames. The exact way the audio signal 1 is represented by the parameters, and the parameters are coded is not important to the invention, many known approaches may be implemented. The invention is directed to the fact that the parameters are differentially coded, even when the number of parameters to be coded differs over successive frames.

A calculating unit 2 receives the audio signal 1 and supplies calculated values 3 every frame. The calculated values 3 represent parameters which should be differentially coded. The coded values should be available in a particular frame. A memory 4 stores the calculated values 3 every frame and supplies the stored values 5. The encoder 6 codes the difference of the calculated values 3 of a present frame and the stored values 5 of the preceding frame and supplies the differentially coded parameter values 7. The differentially coded parameter values 7 may be combined with a coded monaural audio signal in the unit 8 to supply a coded audio signal 9 at the output OUT.

The encoder may contain dedicated hardware or may be a suitably programmed processor which performs the calculations and the other steps.

Fig. 2 shows a schematic representation of a situation wherein the number of parameters during a first frame tl is less than during a second frame t2. The parameters Pl,l to Pl,4 (further referred to as Pl,i) and their associated frequency sub-ranges SFRAI to SFRA4 (further referred to as SFRAi) are shown at the left side for a first frame tl . The parameters P2,l to P2,16 (further referred to as P2,i) and their associated frequency subranges SFRB1 to SFRB16 (further referred to as SFRBi) are shown the at the right side for a second frame t2 succeeding the first frame tl. The parameter Pl,i has a calculated value Ai, and the parameter P2,i has a calculated value Bi. A specific one of the parameters Pl,i or P2,i is obtained by substituting a number for the index i.

The total frequency range is indicated by FR. The subsets of the first calculated value(s) SUSl,i, each comprise a single calculated value Al,i. The subsets of the second calculated value(s) SUS2,i, each comprise more than one (4 in the example shown in Fig. 2) calculated values A2,i.

Consequently, in the associated subsets SUSl,i and SUS2,i, which correspond to the same frequency sub-range SFRAi, always four second calculated value(s) Bi, correspond to one first calculated value(s) Ai. Each one of the four second calculated value(s) Bi, is coded differentially with respect to the same one first calculated value(s) Ai. This means that each of the four coded values is equal to the corresponding second calculated value(s) Bi minus the first calculated value(s) Ai.

Fig. 3 shows another schematic representation of a situation wherein the number of parameters during a first frame is less than during a second frame. In contrast to Fig. 2 now the frequency sub-range obtained by combining the frequency sub-ranges SFRBI to SFRB4 together is not identical to the frequency range SFRAI but slightly smaller. The frequency sub-range SFRB5 occurs partly within the frequency range SFRAI and partly within the frequency range SFRA2. The coded values of the parameters P2,l to P2,4 are coded differentially with respect to the value Al of the parameter Pl,l. The coded value of the parameter P2,5 may be coded differentially with respect to either the value Al or the value A2 of the parameter PI, 2. It is also possible to code the value of the parameter P2,5 as the difference of the value B5 and a weighted sum of the values Al and A2. Preferably, the values Al and A2 are weighted in accordance with the overlap of the frequency range SFRB5 with the frequency ranges SFRAI and SFRA2, respectively.

Fig. 4 shows a schematic representation of a situation wherein the number of parameters during a first frame is higher than during a second frame. Fig. 4 shows a similar situation as shown in Fig. 2 but now the frame tl has a larger number of parameters Pl,i than the succeeding frame t2. The parameters P2,l and P2,2 (further referred to as P2,i) and their associated frequency sub-ranges SFRBI and SFRB2 (further referred to as SFRBi) are shown at the right side for the second frame t2. The parameters P 1,1 to PI, 7 (further referred to as Pl,i) and their associated frequency sub-ranges SFRAI to SFRA7 (further referred to as SFRAi) are shown the at the left side for the first frame tl . The parameter Pl,i has a calculated value Ai, and the parameter P2,i has a calculated value Bi. A specific one of the parameters Pl,i or P2,i is obtained by substituting a number for the index i.

The subsets of the second calculated value(s) SUS2,i, each comprise a single calculated value Bi. The subsets of the first calculated value(s) SUSl,i, each comprise more than one (3 in the example shown in Fig. 4) calculated values Ai.

Consequently, in the associated subsets SUSl,i and SUS2,i, which correspond to the same frequency sub-range SFRBi, always one second calculated value(s) Bi corresponds to three first calculated value(s) Ai. The second calculated value Bi is differentially coded with respect to a calculated weighted mean of the group of associated calculated values Ai. The values Ai are associated with the value Bi if they belong to parameters Pl,i which belong to a frequency sub-range SFRAi which occurs within or at least partly overlaps with the frequency range SFRBi. The weighted mean is calculated as:

M

V gropup =Y / 1a 1ι.V' i-

wherein Ngroup represents a group parameter value, M is the number of parameters belonging to the group of associated calculated values Ai, and qi are the weight functions for which the following holds:

M | ,. =1.

For example, the weights qi are selected to be 1/M, but also the size of the frequency subrange or bin that a certain parameter belongs to is a good choice.

Fig. 5 shows another schematic representation of a situation wherein the number of parameters during a first frame is higher than during a second frame. In the example of Fig. 4, the bins belonging to a group in frame tl always fully fall within a single bin of frame t2. This is not the case in Fig. 5, the bin associated with the value A3 is only partly within the bin associated with the value BI. In differentially coding the value BI with respect to the weighted value, the weights for the value A3 may be selected smaller. Preferably, the decrease of this weight is related to the part of the bin of A3 which is within the bin of B 1 as a percentage of the bins of Al and A2 which are completely within the bin BI. For example, the differential coding as shown in Figs. 2 to 5 is relevant in the parametric coding scheme as presented in E.G.P Schuijers, et.al, "Advances in Parametric coding for high-quality audio", presented at 1st IEEE Benelux Workshop on Model based Processing and Coding of Audio (MPCA 2002), Leuven Belgium, Nov.15, 2002, wherein, because of the quality/bit-rate trade-off, the number of bins used for the IID/ITD/ICC parameters may switch to 10 or 40 frequency bins instead of the typical 20.

Fig. 6 shows a schematic representation of a situation wherein the number of parameters during a first frame is less than during a second frame.

Figs. 2 to 5 showed a variable number of (sets of) parameters Pl,i and P2,i which correspond to a certain fixed frequency region SF. Consequently, if the number of parameters changes, the size of frequency sub-ranges SFRAi or SFRBi will change accordingly such that all the frequency sub-ranges SFRAi or SFRBi together cover the fixed frequency region SF.

Alternatively, as shown in Figs. 6 and 7, each parameter Pl,i and P2,i may belong to a certain frequency region SFRAi and SFRBi, respectively, i.e. the frequency region SFRAi or SFRBi a specific parameter Pl,i or P2,i applies to is constant. If the number of parameters Pl,i and P2,i in a frame tl or t2 changes, the total size of the frequency range covered by all frequency regions SFRAi or SFRBi together changes. This may be the case for the ITD parameter. In the frame tl , the left most column indicates the global parameter(s) GB 1 which represent aspects of the audio signal 1 for the total frequency range FR. The adjacent column shows five parameters (or sets of parameters, for example IID and/or ICC parameters) which are indicated by Cl to C5. Each one of the parameters (or parameter sets) Ci is relevant for an associated frequency sub-range of the total frequency range FR. The frequency sub-ranges together cover the total frequency range FR. The right most column in the frame tl shows two frequency sub-ranges SFRAI and SFRA2 in which two parameters (or sets of parameters) are defined by the values Al and A2, respectively.

In the frame t2, the left most column indicates the global parameter(s) GB2, which correspond to the global parameter(s) GB1. The middle column indicates the five parameters Dl to D5 which correspond to the parameters Cl to C5. The frequency ranges associated with GB1 and Dl to D5 are the same as the frequency ranges associated with GB2 and Cl to C5, respectively. The right most column in the frame t2 shows three frequency sub-ranges SFRBI to SFRB3 and the values BI to B3 of the associated parameters. The frequency sub-ranges SFRBI and SFRB2 associated with the values BI and B2 are identical to the frequency sub-ranges SFRAI and SFRA2 associated with the values Al and A2, respectively. The values BI and B2 are differentially coded with respect to the values Al and A2, respectively. As, in the frame tl, there is no frequency sub-range corresponding to the frequency sub-range SFRB3 in the frame t2, it is not possible to differentially code the value B3 with respect to a value in the frame tl . Still, a data reduction is possible by coding the value B3 with respect to the global parameters) GB2.

Thus, in general, if the number of bins of the parameters with values Ai in a particular frame is smaller than the number of bins of the corresponding parameters with values Bi in the next frame, the differential coding is performed only on bins that actually exist in both frames. Bins that do not have a predecessor are differentially coded with respect to the global values GB2.

Fig. 7 shows a schematic representation of a situation wherein the number of parameters during a first frame is higher than during a second frame.

In the frame tl, the left most column indicates the global parameters) GBl which represent aspects of the audio signal 1 for the total frequency range FR. The adjacent middle column shows five parameters (or sets of parameters, for example IID and/or ICC parameters) which are indicated by Cl to C5. Each one of the parameters (or parameter sets) Ci is relevant for an associated frequency sub-range of the total frequency range FR. The frequency sub-ranges together cover the total frequency range FR. The right most column in the frame tl shows three frequency sub-ranges SFRAI to SFRA3 in which three parameters (or sets of parameters) are defined by the values Al to A3, respectively.

In the frame t2, the left most column indicates the global parameter(s) GB2, which correspond to the global parameter(s) GBl. The middle column indicates the five parameters Dl to D5 which correspond to the parameters Cl to C5. The frequency ranges associated with GBl and Dl to D5 are the same as the frequency ranges associated with GB2 and Cl to C5, respectively. The right most column in the frame t2 shows two frequency subranges SFRBI and SFRB2 and the values BI and B2 of the associated parameters. The frequency sub-ranges SFRBI and SFRB2 associated with the values BI and B2 are identical to the frequency sub-ranges SFRAI and SFRA2 associated with the values Al and A2. The values B 1 and B2 are differentially coded with respect to the values Al and A2, respectively. Thus, in general, if the number of bins of the parameters with values Ai in a particular frame is larger than the number of bins of the corresponding parameters with values Bi in the next frame, the differential coding is performed only on bins that actually exist in both frames. The coding algorithm described with respect to both Fig. 6 and Fig. 7 does not require a signaling in the bit-stream.

For example, in the situation as depicted in Figs. 6 and 7, the Ai and Bi values may represent the number of ITD bins, in a practical realization the number of ITD bins may vary between 11 to 16.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

For example, the absolute number and the change thereof of parameters in corresponding bins of successive frames are examples only. In a practical situation, the number of bins may depend on the actual audio signal and the quality of the audio to be decoded (or the available maximal bit stream). For example, in the situation as depicted in Figs. 6 and 7, the Ai and Bi values may represent the number of ITD bins, in a particular practical realization the number of ITD bins may vary between 11 to 16. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The invention can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS:
1. A method of coding an audio signal, the method comprising calculating values of a first number of first parameters representing aspects of the audio signal at a first instant to obtain first calculated values, calculating values of a second number of second parameters representing the aspects of the audio signal at a second, later, instant to obtain second calculated values, wherein the first number and the second number differ, coding a subset of the second parameters being associated with a particular portion of a frequency range of the audio signal based on a difference of a subset of the second calculated value(s) associated with this particular portion of the frequency range and a subset of the first calculated value(s) associated with substantially this particular portion of the frequency range to obtain differentially coded values of the second parameters.
2. A method of coding an audio signal as claimed in claim 1 , wherein both the first parameters together and the second parameters together cover substantially the same frequency range, and wherein the number of first parameters is smaller than the number of second parameters, the subset of the first calculated value(s) comprises one value for the particular portion of the frequency range being a sub-range of the substantially the same frequency range, the subset of the second calculated values comprises at least two second calculated values, to each one of the second calculated values corresponds one of the differentially coded values being based on the difference of the corresponding second calculated value and the one value.
3. A method of coding an audio signal as claimed in claim 1 , wherein the first parameters together and the second parameters together cover substantially the same frequency range, and wherein the number of first parameters is larger than the number of second parameters, the subset of the second calculated value(s) comprises one value for the particular portion of the frequency range being a sub-range of the substantially the same frequency range, the subset of the first parameters comprises at least two first calculated values, the differentially coded value corresponding to the one value being based on the difference of a mean value of the corresponding first calculated values and the one value.
4. A method of coding an audio signal as claimed in claim 3, wherein the mean value is calculated as a weighted sum of the first calculated values with weights qi.
5. A method of coding an audio signal as claimed in claim 4, wherein the weights qi are equal tol\M, wherein M is the number of first parameters which are associated with a frequency sub-range which at least partly overlaps with the particular portion of the frequency range.
6. A method of coding an audio signal as claimed in claim 4, wherein the weights qi are related to sizes of frequency sub-ranges associated to the corresponding one of the first parameters.
7. A method of coding an audio signal as claimed in claim 4, wherein the weight qi of a first parameter which is associated with a frequency sub-range which does not completely overlap with the particular portion of the frequency range of the second parameter is decreased.
8. A method of coding an audio signal as claimed in claim 1, the method further comprises calculating global values for a total frequency range of the audio signal, and wherein each one of the first parameters and the corresponding one of the second parameters cover substantially the same frequency range, wherein the number of the first parameters is smaller than the number of the second parameters, the subset of the first calculated value(s) comprises a value for each one of the first parameters, the subset of the second calculated values comprises a value for each one of the second parameters, wherein in frequency ranges for which both a first and a second calculated value is calculated, the differentially coded value is based on the difference of the corresponding first and second calculated value, and wherein, in frequency ranges for which a second parameter but no first parameter is calculated, the coded value is based on the difference of the corresponding second parameter and the global values.
9. A method of coding an audio signal as claimed in claim 1, wherein each one of the first parameters and the corresponding one of the second parameters cover substantially the same frequency range, wherein the number of first parameters is larger than the number of second parameters, the subset of the first calculated value(s) comprises a value for each one of the first parameters, the subset of the second calculated values comprises a value for each one of the second parameters, wherein in frequency ranges for which both a first and a second calculated value is calculated, the differentially coded value is based on the difference of the corresponding first and second calculated value, and wherein in frequency ranges for which a first parameter but no second parameter is calculated no coded values have to be determined.
10. An encoder for coding an audio signal and comprising means for calculating values of first parameters representing aspects of the audio signal at a first instant to obtain first calculated values, means for calculating values of second parameters representing the aspects of the audio signal at a second, later, instant to obtain second calculated values, wherein a number of the first parameters and a number of the second parameters differ, means for coding a subset of the second parameters being associated with a particular portion of a frequency range of the audio signal based on a difference of a subset of the second calculated value(s) associated with this particular portion of the frequency range and a subset of the first calculated value(s) associated with substantially this particular portion of the frequency range to obtain differentially coded values of the second parameters.
11. An apparatus for supplying an audio signal, the apparatus comprising an input for receiving an audio signal, an encoder as claimed in claim 10 for encoding the audio signal to obtain an encoded audio signal, and an output for supplying the encoded audio signal.
PCT/IB2003/004864 2002-11-28 2003-10-31 Coding an audio signal WO2004049309A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP02080008.2 2002-11-28
EP02080008 2002-11-28

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
DE2003610449 DE60310449T2 (en) 2002-11-28 2003-10-31 Audio coding
BR0316611A BR0316611A (en) 2002-11-28 2003-10-31 Method for encoding an audio signal encoder to encode an audio signal, and apparatus for providing an audio signal
MXPA05005602A MXPA05005602A (en) 2002-11-28 2003-10-31 Coding an audio signal.
EP20030758495 EP1568010B1 (en) 2002-11-28 2003-10-31 Coding an audio signal
US10536243 US7644001B2 (en) 2002-11-28 2003-10-31 Differentially coding an audio signal
JP2004554728A JP4538324B2 (en) 2002-11-28 2003-10-31 The audio signal encoding
AU2003274520A AU2003274520A1 (en) 2002-11-28 2003-10-31 Coding an audio signal

Publications (1)

Publication Number Publication Date
WO2004049309A1 true true WO2004049309A1 (en) 2004-06-10

Family

ID=32338131

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2003/004864 WO2004049309A1 (en) 2002-11-28 2003-10-31 Coding an audio signal

Country Status (9)

Country Link
US (1) US7644001B2 (en)
EP (1) EP1568010B1 (en)
JP (1) JP4538324B2 (en)
KR (1) KR101008520B1 (en)
CN (1) CN100405460C (en)
DE (1) DE60310449T2 (en)
ES (1) ES2278192T3 (en)
RU (1) RU2005120236A (en)
WO (1) WO2004049309A1 (en)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006072270A1 (en) * 2005-01-10 2006-07-13 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Compact side information for parametric coding of spatial audio
JP2006201785A (en) * 2005-01-19 2006-08-03 Samsung Electronics Co Ltd Method and apparatus for encoding and decoding digital signals, and recording medium
WO2007043841A1 (en) * 2005-10-13 2007-04-19 Lg Electronics Inc. Method and apparatus for signal processing
US7583805B2 (en) 2004-02-12 2009-09-01 Agere Systems Inc. Late reverberation-based synthesis of auditory scenes
US7644003B2 (en) 2001-05-04 2010-01-05 Agere Systems Inc. Cue-based audio coding/decoding
US7720230B2 (en) 2004-10-20 2010-05-18 Agere Systems, Inc. Individual channel shaping for BCC schemes and the like
US7761304B2 (en) 2004-11-30 2010-07-20 Agere Systems Inc. Synchronizing parametric coding of spatial audio with externally provided downmix
US7787631B2 (en) 2004-11-30 2010-08-31 Agere Systems Inc. Parametric coding of spatial audio with cues based on transmitted channels
US7805313B2 (en) 2004-03-04 2010-09-28 Agere Systems Inc. Frequency-based coding of channels in parametric multi-channel coding systems
US8194754B2 (en) 2005-10-13 2012-06-05 Lg Electronics Inc. Method for processing a signal and apparatus for processing a signal
US8204261B2 (en) 2004-10-20 2012-06-19 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Diffuse sound shaping for BCC schemes and the like
US8340306B2 (en) 2004-11-30 2012-12-25 Agere Systems Llc Parametric coding of spatial audio with object-based side information

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1719115A1 (en) * 2004-02-17 2006-11-08 Philips Electronics N.V. Parametric multi-channel coding with improved backwards compatibility
CN101283405B (en) 2005-10-05 2012-10-03 Lg电子株式会社 Method and apparatus for signal processing and encoding and decoding method, and apparatus thereof
CN101390443B (en) * 2006-02-21 2010-12-01 皇家飞利浦电子股份有限公司 Audio encoding and decoding
KR101346771B1 (en) 2007-08-16 2013-12-31 삼성전자주식회사 Method and apparatus for efficiently encoding sinusoid less than masking value according to psychoacoustic model, and method and apparatus for decoding the encoded sinusoid
JP5752134B2 (en) * 2009-10-15 2015-07-22 オランジュ Optimized low-throughput parametric encoding / decoding
EP2477418B1 (en) * 2011-01-12 2014-06-04 Nxp B.V. Signal processing method
KR20140117931A (en) 2013-03-27 2014-10-08 삼성전자주식회사 Apparatus and method for decoding audio

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2982637B2 (en) * 1995-01-17 1999-11-29 日本電気株式会社 Audio signal transmission systems and speech parameter coding apparatus and the decoding apparatus used therefor using spectral parameters
DE19742655C2 (en) * 1997-09-26 1999-08-05 Fraunhofer Ges Forschung Method and apparatus for coding a time-discrete stereo signal
US6029126A (en) * 1998-06-30 2000-02-22 Microsoft Corporation Scalable audio coder and decoder
US6539357B1 (en) 1999-04-29 2003-03-25 Agere Systems Inc. Technique for parametric coding of a signal containing information
CN1149535C (en) * 1999-06-18 2004-05-12 皇家菲利浦电子有限公司 Audio transmission system having an improved encoder
US6446037B1 (en) * 1999-08-09 2002-09-03 Dolby Laboratories Licensing Corporation Scalable coding method for high quality audio
CN1647156B (en) 2002-04-22 2010-05-26 皇家飞利浦电子股份有限公司 Parameter coding method, parameter coder, device for providing audio frequency signal, decoding method, decoder, device for providing multi-channel audio signal

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
EDLER B ET AL: "ASAC - ANALYSIS/SYNTHESIS AUDIO CODEC FOR VERY LOW BIT RATES" PREPRINTS OF PAPERS PRESENTED AT THE AES CONVENTION, XX, XX, 11 May 1996 (1996-05-11), pages 1-15, XP001062332 *
FALLER C ET AL: "BINAURAL CUE CODING APPLIED TO STEREO AND MULTI-CHANNEL AUDIO COMPRESSION" AUDIO ENGINEERING SOCIETY, 112TH CONVENTION, 10 May 2002 (2002-05-10), XP009024737 *
JENSEN J ET AL: "Optimal time-differential encoding of sinusoidal model parameters" SYMPOSIUM ON INFORMATION THEORY IN THE BENELUX, XX, XX, May 2001 (2001-05), pages 1-8, XP002224268 *

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7644003B2 (en) 2001-05-04 2010-01-05 Agere Systems Inc. Cue-based audio coding/decoding
US7693721B2 (en) 2001-05-04 2010-04-06 Agere Systems Inc. Hybrid multi-channel/cue coding/decoding of audio signals
US7941320B2 (en) 2001-05-04 2011-05-10 Agere Systems, Inc. Cue-based audio coding/decoding
US7583805B2 (en) 2004-02-12 2009-09-01 Agere Systems Inc. Late reverberation-based synthesis of auditory scenes
US7805313B2 (en) 2004-03-04 2010-09-28 Agere Systems Inc. Frequency-based coding of channels in parametric multi-channel coding systems
US8204261B2 (en) 2004-10-20 2012-06-19 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Diffuse sound shaping for BCC schemes and the like
US8238562B2 (en) 2004-10-20 2012-08-07 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Diffuse sound shaping for BCC schemes and the like
US7720230B2 (en) 2004-10-20 2010-05-18 Agere Systems, Inc. Individual channel shaping for BCC schemes and the like
US7787631B2 (en) 2004-11-30 2010-08-31 Agere Systems Inc. Parametric coding of spatial audio with cues based on transmitted channels
US7761304B2 (en) 2004-11-30 2010-07-20 Agere Systems Inc. Synchronizing parametric coding of spatial audio with externally provided downmix
US8340306B2 (en) 2004-11-30 2012-12-25 Agere Systems Llc Parametric coding of spatial audio with object-based side information
KR100895609B1 (en) 2005-01-10 2009-04-30 에이저 시스템즈 인크 Compact side information for parametric coding of spatial audio
US7903824B2 (en) 2005-01-10 2011-03-08 Agere Systems Inc. Compact side information for parametric coding of spatial audio
JP2008527431A (en) * 2005-01-10 2008-07-24 アギア システムズ インコーポレーテッド Compact side information for parametric coding of spatial audio
WO2006072270A1 (en) * 2005-01-10 2006-07-13 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Compact side information for parametric coding of spatial audio
JP2006201785A (en) * 2005-01-19 2006-08-03 Samsung Electronics Co Ltd Method and apparatus for encoding and decoding digital signals, and recording medium
US8194754B2 (en) 2005-10-13 2012-06-05 Lg Electronics Inc. Method for processing a signal and apparatus for processing a signal
US8199827B2 (en) 2005-10-13 2012-06-12 Lg Electronics Inc. Method of processing a signal and apparatus for processing a signal
US8199828B2 (en) 2005-10-13 2012-06-12 Lg Electronics Inc. Method of processing a signal and apparatus for processing a signal
WO2007043841A1 (en) * 2005-10-13 2007-04-19 Lg Electronics Inc. Method and apparatus for signal processing

Also Published As

Publication number Publication date Type
EP1568010A1 (en) 2005-08-31 application
ES2278192T3 (en) 2007-08-01 grant
RU2005120236A (en) 2006-01-20 application
KR20050086809A (en) 2005-08-30 application
KR101008520B1 (en) 2011-01-14 grant
EP1568010B1 (en) 2006-12-13 grant
US20060147047A1 (en) 2006-07-06 application
CN100405460C (en) 2008-07-23 grant
CN1717577A (en) 2006-01-04 application
DE60310449D1 (en) 2007-01-25 grant
US7644001B2 (en) 2010-01-05 grant
JP4538324B2 (en) 2010-09-08 grant
JP2006508384A (en) 2006-03-09 application
DE60310449T2 (en) 2007-10-31 grant

Similar Documents

Publication Publication Date Title
US7003448B1 (en) Method and device for error concealment in an encoded audio-signal and method and device for decoding an encoded audio signal
US7536305B2 (en) Mixed lossless audio compression
US6356870B1 (en) Method and apparatus for decoding multi-channel audio data
US20040044534A1 (en) Innovations in pure lossless audio compression
US7693709B2 (en) Reordering coefficients for waveform coding or decoding
US20040044521A1 (en) Unified lossy and lossless audio compression
US7684981B2 (en) Prediction of spectral coefficients in waveform coding and decoding
US20070016418A1 (en) Selectively using multiple entropy models in adaptive coding and decoding
US20090210234A1 (en) Apparatus and method of encoding and decoding signals
US20060004583A1 (en) Multi-channel synthesizer and method for generating a multi-channel output signal
US20040083110A1 (en) Packet loss recovery based on music signal classification and mixing
Schuijers et al. Advances in parametric coding for high-quality audio
US20070081597A1 (en) Temporal and spatial shaping of multi-channel audio signals
US6345246B1 (en) Apparatus and method for efficiently coding plural channels of an acoustic signal at low bit rates
US7831434B2 (en) Complex-transform channel coding with extended-band frequency coding
US8046214B2 (en) Low complexity decoder for complex transform coding of multi-channel sound
US20060235678A1 (en) Apparatus and method of encoding audio data and apparatus and method of decoding encoded audio data
US20050071402A1 (en) Method of making a window type decision based on MDCT data in audio encoding
US20100014679A1 (en) Multi-channel encoding and decoding method and apparatus
US20070174063A1 (en) Shape and scale parameters for extended-band frequency coding
US20110016077A1 (en) Audio signal classifier
US20070172071A1 (en) Complex transforms for multi-channel audio
US8494863B2 (en) Audio encoder and decoder with long term prediction
US20050226426A1 (en) Parametric multi-channel audio representation
WO2004010415A1 (en) Audio decoding device, decoding method, and program

Legal Events

Date Code Title Description
AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 2003758495

Country of ref document: EP

ENP Entry into the national phase in:

Ref document number: 2006147047

Country of ref document: US

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 376889

Country of ref document: PL

Ref document number: 10536243

Country of ref document: US

WWE Wipo information: entry into national phase

Ref document number: PA/a/2005/005602

Country of ref document: MX

Ref document number: 1020057009408

Country of ref document: KR

Ref document number: 1029/CHENP/2005

Country of ref document: IN

WWE Wipo information: entry into national phase

Ref document number: 20038A43447

Country of ref document: CN

Ref document number: 2004554728

Country of ref document: JP

ENP Entry into the national phase in:

Ref document number: 2005120236

Country of ref document: RU

Kind code of ref document: A

WWP Wipo information: published in national office

Ref document number: 1020057009408

Country of ref document: KR

WWP Wipo information: published in national office

Ref document number: 2003758495

Country of ref document: EP

ENP Entry into the national phase in:

Ref document number: PI0316611

Country of ref document: BR

WWP Wipo information: published in national office

Ref document number: 10536243

Country of ref document: US

WWG Wipo information: grant in national office

Ref document number: 2003758495

Country of ref document: EP